This invention relates to a novel method for thermoforming a foamed polymer in sheet form and a system therefor.
In prior art techniques of thermoforming extruded polystyrene sheet, it is common practice to permit the extruded sheet to age for a period of from three to five days in order to obtain the desired foam density reduction. It is also current practice to employ radiant heating to expand the so-aged foam sheets and to heat the same to a temperature suitable for thermoformation. Freshly extruded, unaged foam sheets yield less than a 20% density reduction.
It is an object of the present invention to acheive excellent reduction in foam density regardless of aging time.
It is an additional object of the present invention to present a process which simultaneously treats the foam polymer in order to reduce the density thereof and also bring the foam to the optimum temperature for thermoformation.